Fluoroalkylpolysiloxane lubricants containing organophosphorus additives



United States Patent 3,386,917 FLUOROALKYLPOLYSILOXANE LUBRI- CANTSCONTAINING ORGANOPHGS- PHORUS ADDITIV ES Harry M. Schiefer, Midland,Mich, assignor to Dow Corning Corporation, Midland, Mich, a corporationof Michigan No Drawing. Filed July 13, 1966, Ser. No. 564,756 9 Claims.(Cl. 252-49.9)

ABSTRACT OF THE DISCLOSURE Small amounts of organophosphorus lubricantadditives mixed with fluoroalkylmethylpolysiloxane exhibit markedenhancement of anti-wear characteristics of metal-on-metal.

This application relates to improved fiuoroalkylpolysiloxane lubricantswhich contain organophosphorus additives. The lubricants of thisinvention inhibit the wear of rubbing metal surfaces to a highlysuperior degree, particularly at high loads.

Organophosphorus compounds are known lubricant additives fororganopolysiloxanes. U.S. Patent No. 2,684,336, for example, teaches theuse of a mixture of dimethylpolysiloxane and a trialkyl phosphate as alubricant. However, more than weight percent of the phosphate isgenerally used, resulting in a product which has impaired thermalstability and other properties when compared with the stability of apure organopolysiloxane.

At lower concentrations of organophosphorus compound, little, if any,improvement is noted in the lubricity of such organopolysiloxanes asdimethylpolysiloxane or dimethyl-dichlorophenylmethylpolysiloxane, asshown by the resulting wear.

It has been unexpectedly found that the fiuoroalkylmethylpolysiloxanes,alone among the silicones, exhibit significantly improved wearcharacteristics when small amounts of organophosphorus compounds aremixed with them.

This application relates to a composition. consisting essentially of amixture of (1) 100 parts by weight of an organopolysiloxane fluidcontaining at least 70 mol percent of CH3 (.2. \HE lHzRg units, anyother units present being of the formula (RSiO /2), Or (R SiO Where R isa perfluoroalkyl radical of no more than 12 carbon atoms and R is amonovalent hydrocarbon or halohydrocarbon radical; and (2) from 0.5 to 8parts by weight of a compound selected from the group consisting of R Hfi PO 3 03 P and RP(OR)2 .L

where R is defined above, and n has a value of 2 to 3. R, can be anyperfluoralkyl radical of no more than 12 3,385,917 Patented June 4, 1968ice carbon atoms, e.g., heptafiuoropropyl, perfiuorobutyl,perfluoroisohexyl, perfiuorooctyl, perfluorododecyl, or, preferably,trifluoromethyl.

R can be any monovalent hydrocarbon radical. e.g., alkyl radicals suchas methyl, ethyl, isopropyl, 2-ethylhexyl, or octadecyl; aliphaticallyunsaturated radicals such as vinyl, allyl, ethynyl, butadienyl, or4-hexenyl; or aryl-containing radicals such as phenyl, tolyl, xenyl,naphthyl, benzyl, or 2-phenylpropyl.

R can also be any monovalent halohydrocarbon radical, e.g.,3,3,3-trifiuoropropyl, chloropropyl, bromohexyl, chloroallyl,dibroinophenyl, chlorophenyl, a,a,a-trifluorotolyl, and chloroxenyl.

The organophosphorus additives used herein are esters of phosphates,phosphites, primary phosphonates, or secondary phosphonates. The estersof phosphates and phosphites are preferred, and can be classified asthose organophosphorus compounds which are free of carbonphosphorusbonds.

If desired, a solubilizing agent for the organo-phosphonis compound suchas glycerol trioctoate can be added to the composition of thisinvention. It appears that those organophosphorus compounds which aresoluble or are rendered soluble are more effective at lowerconcentrations than are the less soluble materials. Tris(3,3,3-trifiuoropropyl) phosphate, for example, promotes the lubricityof the organosilicon fluids used herein at concentrations as low as 0.25to- 0.5 weight percent.

The following examples are illustrative only and should not be construedas limiting the invention, which is properly delineated in the appendedclaims.

Example 1 Organophosphorus lubricant additives were added to atrimethylsiloxane endblocked 3,3,3 trifluoropropylmethylpolysiloxanewhich had a viscosity at 25 C. of 232 es, and these nixtures were testedin a shell four-ball tester at 400 F. for two hours at 1200 r.p.m.

The nature of the additive, the weight percent added based on the weightof the silicone fluid, the load applied to the four balls in the tester,and the resulting scar diameter on the balls were measured:

Percent Load Scar Additive Added (kg.) Diameter (Irm1.)

None 4 O. 58 Do 10 0. 40 1. 68 5 4 0. 54 5 10 0. 61 5 40 0. 79 5 4 0. 355 10 0. 48 5 40 0. 78 5 4 0. 52 5 1O 0. 58 5 40 0. 62 3 4 0. 47 3 10 0.52 3 40 0. 65 1. 4 0. 51 1. 1O 0. 64 Do 1. 40 0. 94 Triethyl phosphate 340 0. 87 Trioetyl phosphate 3 40 0. 65 o 10 40 0. 94Tris(fi-ehloroethyl)phosphate 1 40 1. 19

3 4 The following experiments were performed for comparison: (o ruOo 11p c an" The compositions named below were tested as lubricants g in aShell four-ball tester at 400 F. for two hours at OH=OHCI-IP 00 H 1200rpm. The load applied to the four balls in the 5 T 2 12 tester and theresulting scar diameter on the balls were 0 measured: 1 61 (0051117)!Scar Diameter 8 composition 10 That which is claimed is:

gg- 1 1. A composition consisting essentially of a mixture of 1) 100parts by weight of an organopolysiloxane fluid containing at least 70mol percent of (a) Dimetliylpolysiloxane having a viscosity at 25 C.01100 US 0.63 2.0 (b) 05.8 weight percent of (a) above plus 4.2 per- CH3cent of trioetyl phosphate 0. 85 (c) 90 weight percent of (a) above plus10 percent; SiO of trioctyl phosphate 1. 30 2. 0 i (d) A neutralizedfluid hydrolyzate 0184.5 parts by CH,

weight of dimetllyldiehlorosilane, 8.5 parts oftetraellloroplieuyltrichlorosilane, and 7.0 parts of CII R;trinietliylehlorosilane 2. 07 (u) 95weilgl1lt eicei rt of ((1) aboveplus5 percent of z units, any other units present being of the formula e(RSiO (R SiO) or (R SiO where R is a eri9f.lt'tidl l -tl 3 f 1.210fluoroalkyl radical of no more than 12 carbon atoms and R is amonovalent hydrocarbon or halohydrocarbon Example 2 radical; and Thefollowing lubricant additives were added to a z parts by weigh; of gtrimethylsiloxane-endblocked 3,3,3-trifluoropropylmethyl- 5 6 group consmg 0 n polysiloxane having a viscosity at 25 C. of 100 cs., and 11 (3-113, tested in a Shell four-ball tester at 400 F. for one-half R 0 hourwith a load of 20 kg. and a rate of 1200 r.p.m. and RHOR),

The results in each case were as follows:

R OR 0 weight Scar where R is defined above, and n has a value of 2 to3. Additive 3 53 agg 2. The composition of claim 1 where at least 0.9part by weight of ingredient (2) is dissolved in ingredient (1). 3. Thecomposition of claim 1 where ingredient (1) T 3,3,3-t ii '1 h h t 0.4

r g 8 15 a polymer of 3,3,3-tr1fluoropropylmethylsiloxane which 0 eatoft'eslhoshtel 2 2:131 hi a iatty ti id tyrigster i rin eib liyiliarohas endblocks of formu1a.(R3S1O1/2) pane as asolubilizing agent 1 0, 64. The composition of claim 3 where R is methyl.

5. The composition of claim 1 where ingredient (2) is Example 3 40tris(2-ethylhexyl)phosphate. When the following amounts of any of thefollowing gi gg ggg g 35 of damn I Where mgrcdlent (2) 1Sorganophosphorus compounds are added to 100 g. of a 7 Th e compositionof claim 1 where ingredient (2) is fluid organopolysiloxane of theformula tricresyl phosphate 3H3 (3H3 (3H (|JH=CH (Ogl'IgCigSlOg/g) SiloSiO [8'10 OUzSiOqHs CH3 CH3 C3H7 2 CH2 CHzCAFg 10 CHgCFa 20 Hz improvedlubricity on the part of the fluid mixture is ob- The composition ofclaim 1 Where ingredient (2) is tamed: diisopropylhydrogen phosphite.

9. The composition of claim 1 where ingredient (2) is 0rganopho ph r s Cmp n Amount, gfree of carbon-phosphorus bonds.

Dibromophenylhydrogen phosphate 4 Tris(Z-phenylpropyl)phosphite 6References Cited UNITED STATES PATENTS B... 2.6.1. 11a serrate$12.52.;1:: '3 2,684,336 M954 25249-9 See g g T Y} if f i 5 2,832,7404/198 Garden et a]. 252-499 cy y y y g phosphate 6 Exner et al Triphenylphosphate 5 3,109,816 11/1963 Feng et al 252-499 XR Biphenylyldibutylphosphate 5 3, 7,4 3 3/196 Tarrant 25249.6 XR S f t t I 5 Tri(p tbutylphenyl)phosphate 5 3,321,401 5/1967 Ford et a1 25 -499 XR*CFHOHZOHZEWCHW 7 DANIEL E. WYMAN, Primary Examiner.

WARREN H. CANNON, Assistant Examiner.

